Chin strap assembly for helmet



FIG. 1 is a front and left side perspective view of a chin strap assembly for helmet, showing our new design connected to a helmet;

FIG. 2 is a front and left side perspective view thereof, showing our new design connected to a helmet on a user's head;

FIG. 3 is a left side elevational view thereof, showing our new design connected to a helmet on a user's head;

FIG. 4 is a right side elevational view thereof, showing our new design connected to a helmet on a user's head; and,

FIG. 5 is a rear elevational view thereof, showing our new design connected to a helmet on a user's head.

The broken line structure of a helmet and a user's head shown in the drawings is not part of the design sought to be patented. 

The ornamental design for the chin strap assembly for helmet, as shown and described. 